When you install Xfce you will get the standard menu, the panel will be at the top and you will have a panel at the bottom from Xfce with icons. That is NOT plank.
Linux is about freedom.
You do not have to copy me. I am just showing what possibilities you have.
We move the panel from top to bottom. We check out what settings of the panel we can change like transparency.
We delete the bottom panel and replace it with our plank and all its themes.
We change the standard menu with the whisker menu. It has LOADS of settings to tweak even further.